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41 Cards in this Set
- Front
- Back
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which MR sequences are best to eval myelination in ped pts
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depends on age
<8m, T1 >8m, T2 |
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general rules for myelination patterns
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back to front
caudal to cranial middle to peripheral |
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first structures to myelinate
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dorsal brainstem (babies can breathe!)
central corticospinal tracts (can move!) thalamus, lentiform nuclei |
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development and myelination of corpus callosum
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develops from front to back
myelinates from back to front |
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age at which adult myelination is reached
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24 months
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ddx delayed myelination
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in utero insults (ischemia/hypoxia)
infx toxins coagulopathy leukodystrophy |
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pelizaeus MErzbacher dz
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X linked leukodystrophy that leads to neonatal arrest of demylination (can mimic other forms of demyelination)
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effects of hypoxic insult in first and second trimester
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may arrest or alter fruther brain development; hydranencephaly, cortical irregularities
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pathophys of hydranencephaly
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ischemic infarctions of b/l cerebral hemisphere secondary to early compromise of bilateral carotid arteries with preservation of posterior circulation
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etiologies of hydranencephaly
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hypercoag state
placental issues severe in utero infx |
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appearance of hydranencephaly
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little/no supratentorial brain tissue
no rind of cortical gray (distinguishes from severe hydrocephalus) cbl and thalami are preserved |
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how to distinguish hydranencephaly from holoprosencephaly
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no falx in holoprosencephaly, falx is present in hydranencephaly
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where are the border zones in fetus
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they move depending on age
1st -early 2nd trimester: immediate periventricular region lalte 2nd - early 3rd: peripheral WM, cortical gray |
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pathophys of colpocephaly
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peritrigonal WM is injured --> neuronal loss and cystic cavitary atrophy
cysts get incorporated into ventrical wal --> ex vacuo enlargement |
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alobar holoprosenchephaly
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anterior rind of brain tissue and monoventricual that communicates with a dorsal cyst.
thalami are fused no septum pellucidum, CC, or falx. |
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semilobar holoprosencephaly
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partial fusion of hemispheres
CC and septum pellucidum are absent/dysgenic (postior portion usually formed) |
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Lobar holoprosencephaly
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partial absence of frontal interhemispheric fissure.
no septum pellucidum brain otherwise fairly nml |
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common features of all holoprosencephalies
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no septum pellucidum
strongly assoc with schizencephaly, polymicrogyria, pachygyria |
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discriminating sign of alobar holoprosencephaly
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upside down U shaped mantle brain tissue (aka hippocampal ridges)
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ulegyria
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mushroom shaped gyri secondary to subcortical WM infarcts
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HIE
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hypoxic ischemic encephalopathy
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sequellae of hie
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delayed myelination, thin CC (tapers at splenium)
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appearance of acute (<3d) after profound perinatal HIE
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deep gray matter becomes iso to WM
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appearance of 3d-3w after profound perinatal HIE
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high T1, low T2 in GB, thalamus, may reflect blood products
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appearance of 3w-3m after profound perinatal HIE
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variable signal within BG
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appearance of 3m after profound perinatal HIE
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evolving injury to cenral GM, thalami,m pre and postcentral gyri
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ppearance of profound postnatal HIE
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sparing of perirolandic cortex (pre and postcentral gyri)
lrg portions of hte cortex, GP, putamen, caudate, and thalami are afffected |
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white cbl sign
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on CT severe HIE shows decreased attenuation in cerebral hemispheres b/c of edema
cbl spared and looks white |
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dark cbl sign
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cbl looks dark on T2b/c of edema in the rest fo the brain 2/2 severe HIE
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most sensitive way to dx ischemic brain damage
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MR spect - look for lactate peak
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SOD
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hypoplasia of CN II withcomplete/partial absences of sseptum pellucidum --> squared off appearance of frontal horns
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what does fat floating in CSF space represent
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ruptured dermoid
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pathophys of encephalocele
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failure of skull and dura to close over brain
intracranial contents herniate through defect |
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most common locations for encephalocele
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occipital > fronto-eethmoidal, parietal, sphenoidal
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presentation of sphenoid encephalocele
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NP mass containing herniated 3rd vent, hypothalamus, optic chiasm
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presentation of fronto-ethmoidal encephalocele
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craniofacial anomaly
callosal abn |
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diff btwn meningocele and encephalocele
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meningocele: leptomeningeal herniation
encephalocele: brain + leptomeninges |
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which craniosynostosis --> premature closure of sag suture
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dolichocephaly (looks like a football, long AP, narrow transverse)
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coronal suture synostosis
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brachycephaly (looks like Stewie from family guy)
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metopic suture synostosis
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trigonocephaly (pointed forehead)
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synostosis of all sutures
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clover-leaf skull
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